1. Field of the Invention
The invention relates to a method for configuring a field device. Furthermore, the invention relates to a system for parameterization of a field device with a parameterization unit.
2. Description of Related Art
In modern process automation, field devices are used mostly for monitoring process variables and as actuators for influencing the processes. Field buses, for example, are used for the communication between the field devices and a control room, for which different data protocols are used for transmitting measurement and control data. In addition, it is usually also provided that the field devices themselves have display units, so-called screens, via which, for example, the measurement data or other values of the field device can be represented. Thus, many field devices have at least two output options: on the one hand, an interface for connecting the field devices to a field bus connection for data link, and, on the other hand, a display unit for on-site presentation. Occasionally, an input device, e.g., in the form of some buttons, is present on the field device or, for example, a configuration unit in the form of a so-called hand-held device (PDA) or a portable computer in the form of a laptop can be connected directly via a service interface.
Problems can arise when the data connection is not secure and when the use of the field device is relative to security. If the field device is mainly being configured, i.e., if it is being set to how it should function, then it is extremely important that the parameter values are set safely in the field device. The respective safety requirements, and if applicable, the requirements to meet the SIL (Safety Integrity Level) standard, important especially in process automation, are relevant.
The problem of unreliable data links or data storage, particularly in applications relative to safety, has already been dealt with as a part of the prior art.
The U.S. Pat. No. 6,445,965 B1 discloses a method for the monitoring of safe conditions of devices within a system. The devices are, in each case, depending on the type of operation, assigned parameters that are to be monitored by sensors. For easy interchangeability of components, the parameter values are stored in a data memory. A checksum is generated and compared with the current values so that the parameter values cannot be changed without authorization.
In U.S. Patent Application Publication 2007/0124115 A1, an automation system with field devices on a field bus is described, in which safety-related data are transmitted using different mechanisms, e.g., the use of checksums.
European Patent Application EP 2246761 A1 describes a method for monitoring the parameters of an automation component, wherein test values of the control unit and the component are compared to one another. The checksums are formed not using the parameter values, but rather using the difference between the newly set parameter values and the previous parameter values.
The International Patent Application Publication WO 2006/053668 A2 describes a method for configuration of a device, wherein the parameter values are retrieved at least once to check the device parameterization.